Some machines that prepare and dispense mixed beverages include a mixing chamber arranged in a housing. In some cases, the mixing chamber has a filling opening in its upper region and at least one extract container arranged above the filling opening to accommodate coffee or other powdery soluble extracts. The housing also has a metering device for the extract container, allowing for metering the chosen powdery soluble extract into the mixing chamber via a metering opening. Inside the mixing chamber, the extract supplied from the metering device is mixed with a hot liquid such as water to produce a beverage.
Some such machines have more than one extract container, which can be filled with various powdery soluble extracts. According to the user's selection, a portion of the chosen extract will be supplied to the mixing chamber from the appropriate extract container and mixed therein with a liquid, such as hot water, to make a beverage. However, since the number of extract containers must be quite limited for reasons of overall size, a selection can only be made from a few different extracts for mixed beverages. The wide range of powdery soluble extracts for mixed beverages which are commonly available can thus not be utilized. Examples of such mixed beverages from soluble extracts are coffee, white coffee, espresso, decaffeinated coffee, chocolate, cappuccino, tea, milk and coffee with cocoa. It is desired to make such machines more flexible in the choice of available beverage selections and beverage additives.
In many such machines, the powdery soluble coffee extract and, if necessary, milk powder, are dispensed into a funnel-shaped mixing chamber and dissolved by means of hot water which flows in via the hot water supply. For mixing the hot water supply with the coffee extract the hot water supply is directed into the mixing chamber approximately at right angles to the axis of rotation of the first cream rotor and approximately tangentially to the side wall of the mixing chamber. To form a circulating flow in the mixing chamber, the hot water must flow into the mixing chamber at a certain minimum pressure, such as by direct connection to a pressurized water pipe (potentially limiting flexibility of positioning and moving such machines once installed), or by incorporating a pump. Other means of improving the mixing and aeration of hot beverages in such machines are desired, preferably at lower cost and greater convenience.